A novel small dynamic solar thermal desalination plant with a fluid piston converter

Analysis by simulation of a solar still integrated in a greenhouse roof

Exergy performance evaluation of a basin-type double-slope solar still equipped with phase-change material and PV/T collector

Purpose: Access to clean and potable water supply is the priority of many nations including the government of Nigeria towards socio-economic emancipation of the people. Due to increasing population expansion and water pollution, shortage of freshwater has become very common to many nations, particularly to the developing countries. To overcome the growing freshwater shortage, desalination has been proven to be the best alternative option towards freshwater provision for domestic and industrial applications. Desalination could be either thermal or electric methods which include multi-stage flash distillation (MSFD), multiple-effect distillation (MED), reverse osmosis (RO), or solar desalination. The innovation of solar still technology in recovery of fresh water from saline waters makes solar desalination simple and economical. A survey of socio-economic importance of solar energy desalination of saline lake waters at Uburu and Okposi communities, Ebonyi State, South eastern, Nigeria was conducted.
 Methodology: A survey research design was adopted for the study in order to address an age long tradition of fuel wood utilization in salt processing activity by the local women folk of Uburu and Okposi communities using saline water from the local lakes.
 Results: The survey showed that about 1,200 women were involved in the salt production activity utilizing about 26,000 tons of fuel wood per year. Translating this into monetary terms amounts to about US$$1.5 million per year. Socio-economic lives of people in the communities were negatively affected because fuel wood utilization in salt production adversely results to deforestation, environmental pollution and high cost of fuel wood in the communities. The quality and quantity (output) of salt recovering process were not commiserating to time, energy and monetary input in the process. It was observed that the distillate (freshwater portion) of the salt recovery from the saline water was not considered as an important component of the salt extraction process. This is because the salt producers were only interested on the salt extract as the only useful output of the extraction process. Recovery of freshwater component of the process could be an additional valuable income if considered.
 Unique Contribution to Theory, Policy and Practice: For sustainable salt production and freshwater recovery from the process solar desalination method was recommended for salt processing in the communities. The incorporation of solar desalination system into the age long traditional known method of salt processing will enhance salt production and boast socio-economic activities in the communities. A study of this kind is likely to help solve a major problem of acute water shortage in some communities whose water bodies are salty. The study could be a useful tool for policy makers in making rational policy that would improve and enhance salt and fresh water production as an enterprise.

This paper targets to consider a hybrid cycle consisting of a solid oxide fuel cell and an Ericsson thermal engine that provides drinking water by connecting to a reverse osmosis desalination unit. First, a parametric assessment was performed on the target functions, including power, exergy destruction density, and fresh water production. After conducting studies on the composition of these target functions, three scenarios are defined for the simultaneous optimization of the mentioned functions. The first scenario targets to optimize the exergy destruction density (Exd) and the fresh water production (mf). In this scenario the exergy destruction and fresh water production have a better condition in the FUZZY approach, that the maximum value of the exergy destruction density and fresh water production are 450.879 (W m−2) and 2.078 (kg s−1), respectively. The second scenario attempts to optimize the power (P) and the fresh water production (mf). According this scenario the power has the highest value in the FUZZY that is equal to 531.965 (KW), besides the fresh water production achieves to a maximum value in TOPSIS which it value is 0.365 (kg s−1). The third scenario considers optimizing the power (P), the fresh water production (mf), and the exergy destruction density (Exd). The power (P) has permanent value in three decision-making which is equal 311.105 (KW), also the fresh water production (mf) is 1.816 (kg s−1) in three decision-making and besides the exergy destruction density (Exd) has a constant value in three decision-making which is 30.439 (W m−2). In all three scenarios, the decision-making methods, such as TOPSIS, FUZZY, and LINMAP were appropriate to specify the ultimate solution between the beam fronts.

Coupling a small-scale concentrated solar power plant with a single effect thermal desalination system: Analysis of the performance

Enhancement of solar desalination by humidification-dehumidification technique

In humidification-dehumidification water desalination (HDHWD) systems, the direct contact heat exchanger serves as a crucial component that significantly affects the efficiency of converting saline or brackish water into fresh water. This research focuses on the development of a numerical model to simulate heat and mass transfer processes occurring between hot sprayed seawater and air within a direct-contact humidifier. The model was employed to examine the influence of various operational parameters, including the inlet temperature of seawater, seawater mass flow rate, inlet air temperature, and air mass flow rate, on the humidifier’s effectiveness and the rate of freshwater evaporation. The results demonstrate that the optimal humidifier effectiveness is attained when the mass flow rate ratio of seawater to air is unity. Additionally, the inlet temperature of seawater and the mass flow rate ratio between seawater and air emerged as the most critical factors governing the humidifier’s freshwater production capacity. The maximum value of water evaporation is 341 kg/hr that occurs at operating conditions of inlet seawater temperature of 90°C, inlet air temperature of 30°C, inlet air relative humidity of 50%, and seawater to air mass ratio of 5. The findings found that freshwater productivity improves by approximately 25% when the seawater temperature is increased by 10%.

New experimental aspects of the carrier gas process (CGP)

A novel integrated system for fresh water production in greenhouse: Dynamic simulation

The integration of renewable energy sources to power seawater desalination is crucial to mitigate CO 2 emissions and to face the increasing challenges that are stressing fresh water resources depletion. In particular wind energy is one of the most cost-effective forms of renewable energy with a high potential to reduce the seawater desalination”s environmental impact. While most applications are aimed at using conventional wind technologies to produce the electricity required by the desalination processes, wind turbines with hydraulic transmission can bring new opportunities to avoid the multiple energy conversion steps and make fresh water production from wind energy more simple and cost-effective. This paper elaborates on two potential configurations, numerical modelling and possible control strategies which are able to directly combine a horizontal axis wind turbine rotor, a hydraulic transmission and a seawater reverse osmosis (SWRO) desalination unit. The integration of an ideal pressure exchanger as energy recovery devices (ERD) to increase the operating efficiency of the SWRO unit is analysed. Results are shown for the most relevant operating conditions of the integrated system in terms of wind speeds, pressures, brine salinity and fresh water productions. Intermediate results are also shown for the dynamic analysis and simulation of the wind powered direct-driven SWRO system subject to turbulent wind speed conditions.

Preliminary assessment of innovative seawater reverse osmosis (SWRO) desalination powered by a hybrid solar photovoltaic (PV) - Tidal range energy system

Improving the saline water evaporation rates using highly conductive carbonaceous materials under infrared light for improved freshwater production

Comparison of different operation modes of a single effect thermal desalination plant using waste heat from m-CHP units

This study introduces an innovative approach to saline water desalination using a stationary compound parabolic concentrator (CPC) to power a low-temperature thermal desalination (LTTD) system. The integration of CPC into LTTD was thermodynamically modeled and simulated under tropical climatic conditions. Key parameters, including hot feed saline water temperature, temperature gradient, cold-water inlet temperature, feed saline water flowrate, flash chamber pressure, and varying salinity levels, were examined for their impact on freshwater production. Additionally, the design requirements for CPC arrays and economic considerations were thoroughly analyzed to achieve a large-scale freshwater production capacity of 1000 L/day. The results showed that increasing the thermal gradient, feed saline water temperature, and flowrate, while decreasing the flash chamber pressure, significantly enhanced freshwater production. For example, as the temperature gradient increased from 7 °C to 20 °C, the average freshwater yield rose from 75.23 L /h to 120.19 L /h. Achieving the target freshwater production required 126 to 152 CPC units with an area of approximately 3 m2 for hot feed saline water temperatures between 37 °C and 50 °C. Furthermore, increasing the feed saline water flowrate from 7500 L /h to 22,500 L /h resulted in a 66.48% increase in freshwater yield. Reducing flash chamber pressure from 12.35 kPa to 4.5 kPa led to a substantial increase in potable water production, ranging from 21.65% to 90.9% across different temperature gradients. The study also evaluated the effects of salinity levels, finding a slight decrease in freshwater production with higher salinity.

Design and test of a single effect thermal desalination plant using waste heat from m-CHP units